Carbon-Filled Polymer Blends for PEM Fuel Cell Bipolar Plates

Abstract

Carbon-filled polymer blends with a triple-continuous structure, consisting of a binary (or ternary) polymer blend and carbon particles, have great potential to provide injection moldable PEM fuel cell bipolar plates with superior electrical conductivity and sufficient mechanical properties. Four carbon nanotube (CNT)-filled polymer blends, i.e., CNT-filled polyethylene terephthalate (PET)/polyvinylidene fluoride, PET/polypropylene, PET/nylon 6,6, and PET/high-density polyethylene blends, have been injection molded and characterized in terms of their microstructures, electrical conductivities, and mechanical properties. Effects of the thermodynamic driving force, rheology of the polymer blend, and injection molding conditions on the distribution of CNTs in the blends have been examined. The simultaneous improvements in the electrical conductivity and mechanical properties of carbon-filled polymer blends over carbon-filled polymers have been investigated based on the CNT distribution in the polymer blends. The results unambiguously indicate that the preferential location of CNTs in one of the continuous polymer phases in the polymer blend is highly desirable for both mechanical and electrical properties. Future directions in this emerging area are discussed.

Notes

Acknowledgments

The author is indebted to Professors Frano Barbir, Montgomery Shaw, and Lei Zhu for fruitful discussion over a wide range of the topics related to this research. The author is also grateful to many of his former and current students, especially Ms. Man Wu, Dr. Daniel Goberman, Mr. Hong Luo, and Dr. Juan Villegas, for carrying out various experiments related to this project. Finally, the financial support from the US Army (contract #: DAAB07-03-3-K415) through the Connecticut Global Fuel Cell Center is greatly appreciated.